JPS58121875A - Television receiver - Google Patents

Abstract

PURPOSE:To prevent interference of mutual reception, by automatically switching the reception and power supply, in detecting either an SHF satellite television broadcast reception channel selection switch or a U/V television broadcast reception channel selection switch is operated. CONSTITUTION:In selecting either the SHF satellite television broadcast or the U/V television broadcast, a switching device 15 is operated with a switching control circuit 17. Simultaneously, power supply from the power supply 32 is switched. In switching to receive the SHF satellite television for the switch 15, the power supply voltage is applied to only an FM demodulation circuit 9, and the power supply of a U/V television broadcast reception circuit tuner 28 from a terminal 14 is turned off by the switching control circuit. Depending on the channel selection of any channel selection switch, a control voltage is generated from voltage generators 27, 31, then the switching control circuit is controlled and the operated reception system is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a signal processing circuit for receiving SHF satellite television broadcasting for tlHF/VHF television (hereinafter referred to as U/V
Regarding television receivers that are incorporated with signal processing circuits for broadcast reception (referred to as televisions), we have developed television receivers that can prevent interference due to mutual interference between two signal processing circuits and that can improve operability. This is what we provide.

First, a basic block diagram of an SHF satellite television broadcast receiver is shown in FIG. Here, 1 is an antenna for receiving SHF TV signals, 2 is its output terminal, 3 is a down converter and inverter that converts the SHF TV signal into a UHF TV signal, 4 and 6 are its input/output terminals, and 6 is the signal for outdoor use. Reference numeral 7.8 is the input/output terminal of the Cape Nope, which is led indoors from the cape, 9 is the FM demodulation circuit including the second frequency conversion circuit, and 10.11 is the input/output terminal. The signals of each part are FM modulated 5) (F signals at terminals 2 and 4, FM modulated UHF signals at terminals 5, 7, 8 and 10, and baseband video signals at terminal 11. .

Next, we will convert the receiving circuit for such SHF television broadcasts into U/V.
FIG. 2 shows an example of the configuration of an inner-type receiver incorporated with a television broadcast receiving circuit. Here, 12 is a signal processing circuit for conventional U/V television broadcasting, and 13 and 14 are its input/output terminals. AM-modulated VHF television signals and UHF television signals are inputted from an input terminal 13 and outputted to an output terminal 14 as video signals. Reference numeral 16 denotes a switch that selects whether to receive SHF satellite television broadcasting or U/V television broadcasting and applies a video signal to cathode ray tube 16, and 17 is a changeover operation switch.

Still 1s [U/V TV broadcast reception channel selection ↓Circuit 9
, 18, the receiving channel is selected by switching the oscillation frequency of the local oscillator in the receiving channel. In this way, a receiver is constructed which can selectively receive both SHF satellite television broadcasting and conventional U7Δ television broadcasting.

However, it has been found that the following interference occurs in this built-in receiver. The following equations show that the interference signal at the right frequency mixes into the left frequency and causes interference.

−'SS ”−2xfUL ・−・−(1)f
SI = fSL-2xfUL -・----(2)
fUS”-fSL-fUL (3)
fuI=fsL-2xfUL song-(4) Here, fs
s, fsL, and fSI are S as shown in FIG.
The frequency of the first intermediate frequency input signal to the second mixing element 20 of the second frequency conversion circuit in the FM demodulation circuit 9 for receiving HF satellite television broadcasting.

Frequency of the local oscillation signal from the second local oscillator 21.

This is the frequency of the second intermediate frequency of the output of the second mixing element 20. Also, fUs, fUL, and fUI are the fourth
As shown in the figure, the frequency of the local oscillation signal from the U) IF television signal frequency 2 local oscillator 23 to the mixer 22 in the signal processing circuit 12 for U/V television broadcast reception;
The intermediate frequency of the output of the mixer 22 is 58 MHz.

Here, as an example of interference in the first equation, it is shown that harmonics twice the fuL are mixed into fss and cause interference, but the same applies to the other equations 2 to 4. Disturbances in thinking occur.

Therefore, an object of the present invention is to provide a built-in SHF and UHF/VHF receiver that can prevent these interferences.

Hereinafter, one embodiment of the present invention will be described with reference to one page. It should be noted that parts corresponding to those in FIG. 2 will be described with the same reference numerals.

In FIG. 6, 24 is a part of the second frequency converter in the FM demodulation circuit e for receiving SHF satellite television broadcasting, 26 is a first intermediate frequency amplifier, and 26 is a second intermediate frequency amplifier. . Reference numeral 27 denotes a DC voltage generation circuit for tuning, which generates a DC voltage corresponding to the operation of the tuning switch 19, sets the oscillation frequency of the local oscillator 21, and generates a selection corresponding to the tuning switch. A game is played.

Further, 28 is a part of the tuner in the signal processing circuit 12 for U/V television broadcast reception signals, and 29 is a part of the tuner for the U/V television broadcast reception signal.
V TV signal amplifier, 3o is intermediate frequency 58MHz
This is an amplifier. Reference numeral 31 denotes a DC voltage generation circuit for tuning, which generates a DC voltage corresponding to the operation of the tuning switch 18, sets the oscillation frequency of the local oscillator 23, and performs tuning corresponding to the tuning switch. It will be done.

Here, 5) (it is necessary to select one of the video signals of F satellite television broadcasting and U/V television broadcasting and supply it to the cathode ray tube 16, and for this purpose, the switching control circuit 17 switches the switch 16. At the same time, this device also switches between supplying the power from the power generator 32 to the FM demodulation circuit 9 side and the U/V television signal processing circuit 12 side. In this case, when the switching control circuit 17 switches the switch 16 so that the video signal of the SHF satellite television broadcast from the terminal 11 is applied to the cathode ray tube 16, the power supply voltage from the power supply generator 32 is set to SHF. It is supplied only to the FM demodulation circuit 9 side for satellite TV broadcast reception, and on the other hand, it is supplied to terminal 1 by the switching control circuit.
4 to the cathode ray tube 16.
When the switch 15 is switched so that the voltage is applied to the U/V television broadcast reception signal processing circuit 12 side, the power supply voltage from the power supply generator 32 is switched in conjunction with each other so that the power supply voltage is supplied only to the signal processing circuit 12 side for receiving U/V television broadcasting. do. Note that the power generator 32
The power supply voltage generated and supplied by 5) is at least the power supply for the second frequency conversion circuit 24 of the F satellite television broadcast reception system or the tuner 28 of the U/V television broadcast reception system.

Furthermore, in order to improve the operability of switching as described above, this device determines whether the channel selection switch 19 for the SHF satellite television broadcast reception system is operated or the selection switch for the U/V television broadcast reception system at the time of channel selection. Depending on whether the station switch 18 is selected, control power is generated from each DC voltage generator 27, 31, and this controls the switching control circuit 17 to receive the television broadcast of the operated station. The switch 15 is switched so that the output video signal from the FM demodulation circuit 9 for the system or the signal processing circuit 12 is supplied to the cathode ray tube 16, and the FM demodulation circuit 9 for the television broadcast receiving system is operated. Alternatively, the power generator 32 is switched so as to supply operating power only to the signal processing circuit 12.

In this way, there is no need to provide and operate a separate switch to switch between receiving SHF satellite television broadcasts and U/V television broadcasts, and simply operate the channel selection switches 19 and 18. This makes it possible to improve operability.

By doing this, you can receive SHF satellite television broadcasting by operating the channel selection switch 19 and display it on the cathode ray tube 16.
When displaying the received image, power is not supplied to the tuner 28 of the signal processing circuit 12 for U/V television broadcast reception, and the transmission from the U/V television broadcast reception system to the SHF satellite television broadcast reception system is interrupted. Interferences such as those in Types 1 and 2 are prevented. When receiving U/V television broadcasting and displaying the received image on the cathode ray tube 16, interference such as those in types 3 and 4 from the SHF satellite television broadcasting receiving system to the U/V television broadcasting receiving system is prevented.

Thus, when receiving any television broadcast,
Interference from the other receiving system is eliminated, and a good image receiving condition can be obtained.

Note that the power supply voltage generated from the power supply generator 32 is supplied to the second frequency conversion circuit 24 or the tuner 28;
The purpose of controlling by switching the power supply voltage is to selectively operate the local oscillation of each receiving system, so even if the power supply voltage applied only to the oscillator of each receiving system is switched. good. However, if you switch the power supply voltage to the entire surrounding circuit, you can not only stop the other local oscillation and eliminate interference, but also reduce the power applied to the entire surrounding area, resulting in a power saving effect. can also be expected.

As described in 2 below, according to the present invention, a circuit for receiving SHF satellite television broadcasting and a circuit for receiving UHF satellite television broadcasting, each including a frequency converter,
or V) (F) In a television receiver integrated with a circuit for receiving television broadcasts, when receiving one television broadcast, the power supply to the local oscillator in the circuit for receiving the other television broadcast is stopped. Therefore, when receiving either television broadcast, it is possible to receive a good image without interference from the other circuit.

Furthermore, the switching of the reception and the switching of the power supply are
It detects whether the channel selection switch for receiving HF satellite TV broadcasts or the channel selection switch for U/V TV broadcast reception is operated and automatically switches the switch, resulting in easy operation with fewer operations. It is something that can be obtained.

[Brief explanation of drawings]

Figure 1 is a block diagram of a circuit for receiving SHF satellite television broadcasting, Figure 2 is a block diagram of a conventional television receiver,
3 and 4 are partial circuit diagrams thereof, and FIG. 5 is a block diagram of a television receiver according to an embodiment of the present invention. 9...FM demodulation circuit for SHF satellite TV broadcast reception, 1o...Input terminal, 11...Output terminal, 12...U/V TV broadcast Receiving signal processing circuit, 13... Input terminal, 14...
...output terminal, 16...input/switcher, 16...
...Cathode ray tube, 1 completion...Switching control circuit, 18.
19...Tuition selection switch, 20.22----
Mouse mixer, 21, 23...Local oscillator. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 0 Figure 5 9

Claims (1)

[Claims] A circuit for receiving SHF satellite television broadcasting, each including a frequency converter, and a circuit for receiving UHF or -1'V HF television broadcasting are integrated, and the above-mentioned circuit for receiving SHF satellite television broadcasting is constructed. and the output signal of the circuit for receiving UHF or VHF television broadcasting and supplying the selected one to the cathode ray tube. Alternatively, V) (provide a channel selection switch for switching the reception channel separately for F-Tele and the broadcast reception circuit, and switch the channel according to which channel selection switch of the TV broadcast reception circuit is operated. The television receiver is provided with a switch circuit for switching the switch to the operated side and cutting off power supply to at least a local oscillator in a circuit for receiving television broadcasting on the side not selected by the switch.